//1419.数⻘蛙
import java.util.HashMap;
import java.util.Map;


class Solution {
    public int minNumberOfFrogs(String c) {
        char[] croakOfFrogs = c.toCharArray();
        String t = "croak";
        int n = t.length();
        int[] hash = new int[n]; // 数组模拟哈希表
        Map<Character, Integer> index = new HashMap<>(); // [x, x这个字符对应的下标]
        for (int i = 0; i < n; i++)
            index.put(t.charAt(i), i);
        for (char ch : croakOfFrogs) {
            if (ch == t.charAt(0)) {
                if (hash[n - 1] != 0) hash[n - 1]--;
                hash[0]++;
            } else {
                int i = index.get(ch);
                if (hash[i - 1] == 0) return -1;
                hash[i - 1]--;
                hash[i]++;
            }
        }
        for (int i = 0; i < n - 1; i++)
            if (hash[i] != 0)
                return -1;

        return hash[n - 1];
    }
}
